Protective device for electrical apparatus



July 17, 1923.- 1.462.346

- C. H. KLINE PROTECTIVE DEVICE FOR ELECTRICAL APPARATUS Filed Feb. 16 1921 Figyf I Inventor": Charles H.Kline.

by His Attorney.

Patented July 17, 1923.

UNITED STATES PATENT OFFICE.

CHARLES HOWARD KLINE, OF PITTSFIELD, MASSACHUSETTS, ASSIGNOB TO GENERAL 1 ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROTECTIVE DEVICE FOR ELECTRICAL APPARATUS.

Application filed February 16, 1921. Serial No. 445,488.

' To all whom it may concern:

Be it known that 1, CHARLES HOWARD KLINE, a citizen of the United States, residing at Pittsfield, in the county of Berkshire, State of Massachusetts, have invented certain new and useful Improvements in Protective Devices for Electrical Apparatus, of which the following is a specification.

'My invention relates to a protective device for encased electrical apparatus such as transformers and the like.

It has been recommended for standard practice that transformers and like apparatus always be installed with adequate protecting devices such as lightning arresters, etc., to take off safely to ground the peak voltages which may arise during surges or other transient phenomena.

This recommendation has resulted in reviding encased electrical apparatus, suc as transformers, with a type of safety bushing for the high voltage leads, which is designed to permit the peak voltage accompanying the transient to discharge itself from the high voltage leads to the casing at the bushing, the casing being constructed to discharge to ground upon the attainment of a predetermined potential. An arrangement embodying this protective system was first disclosed in the U. S. Letters Patent No. 1,310,054, issued in the name of L. R. Brown, July 15, 1919.

The. object of my invention is to provide an improved arrangement of parts designed to accomplish this scheme of protection in a more precise and economical manner than that heretofore proposed.

In accomplishing the object of my invention I provide the apparatus to be protected with an improved arran ment in the high voltage bushings adapte to permit the discharge of the peak voltage from high voltage leads'to casing across a sphere gap, at the same time providing an improved secondary gap adapted toper'mit a discharge from the casing to ground.

For a more complete understanding of the nature and objects of my invention reference should be had to the following detailed description taken in conjunction with the accompanying drawing in which:

Fig. 1 shows an encased transformer, chiefly in vertical section, equipped with a protective system arranged in accordance with my invention. Figs. 2 and 3 show details; while Fig. 4 is an explanatory diagram.

Referring now to the drawing, 10 denotes a casing containing a transformer 11 which is adapted to be submerged in oil or other suitable fluid insulating material.

The high voltage leads 12 pass into the casing to the high voltage winding P (see Fig. 4;) ofthe transformer through bushin 13 depending from pockets 14 formed in t e casing wall near the top as shown. In similar fashion the low voltage loads 15 pass out of the casing from the transformer through the preferably elongated bushing 16 shown depending from a suitably elongated pocket 17 likewise formed near the top of the casing. The low voltage windings SS are shown in Fi 4 as having what is electrically their mi dle point connected to ground through the connection shown at 19, which leads from one side of each of the sections 5'.

The protective system for this ap aratus comprises the sphere gap at 20 (see ig. .2) in the high voltage bushings whereby the peak voltage of transients may discharge from leads 12 to the casing, and a secondary gap at 21 whereby the charge on the casin may be dissipated by discharging to groun by way of conductors 22, 23 and 19.

The sphere gap 'at 20 is provided by stripping a small portion of a lead 12 where it passes through a bushing 13 and forming thereon a conducting spherical body or enlargement as shown at 30. The bushing 13 is formed tohave an interior chamber 31 adapted to house this stripped portion of the lead 12. The cylindrical wall of this chamber is perforated, preferably at one point as shown at 32, opposite the spherical body 30, and has an exterior conducting collar or segment 33 fitted thereover which is provided with a spherical protuberance 34 projecting into the perforated opening at 32. When the bushing 13 is in place the segment 33 is conductively connected to the casin wall; the bushing being preferably secure by a filling of compound or other insulatdetermined by the positionsof the spherical mg material, as shown at 35. The lead 12' suitable manner, wedges at 36 assisted body 30 and spherical protuberance 34 is thus provided which may arc'over without injury to the parts. Since the creepage (11$- tance is about the walls of chamber 31 1t is seen to be materially greater than the sparking distance of the gap. This arrangement therefore greatly increases the reliabllity of the action of the gap in this confined space.

The secondary gap at 21 is preferably formed from two conducting discs 41 and 42 having central protuberances 43 and 44 disposed toward each other and spaced apart a predetermined distance b 1 the annular 1nsulatin member 45 in w ich the discs are secure The conductor 22 (see Fig. 3) 1s extes riorly secured to one disc, disc 42 in the 1nstance shown; while a threaded stud which is secured exteriorly thereto pro ects fromthe other disc. This stud is arranged to project through the casing! wall 10 and is secured therein in a convenient and conducting manner.

In operation: The arrangement provided permits the peak voltage of translents to discharge from the line to the casing 10 by arcing across the sphere ga at 20 when a certain maximum eak va ue is attalned which is predetermined by the gap setting provided in the desi ThlS value of course takes into consideration the max1- mum stresses that it is desired to protect the line and windings of the transformer from. The secondary gap at 21, as already stated, permits the discharge from casing to ground by way of conductors 22, 23 and 19; hence, when the casing attains a certain maximum potential by charges accumulated from discharge across gap 20, which potentlal 1s predetermined by the distance WhlCh oh tains between the adjacent protuberances on discs 41 and 42, a discharge to ground across ga 21 will take place.

y the arrangement of parts above described, it is seen that the line and the encased electrical apparatus are provided with a protective system adapted to function 1n a reliable and precise manner to relieve undue stress at very definitely predetermined maximum potential values.

Having now described an embodiment of my invention which is at present the best means known to me for carrying the same into effect, I would have it understood that this is merely illustrative, and that I do not mean to be limited thereby to the precise details shown nor restriced in the choice of recognized equivalents exce t'as defined in my claims hereunto annexe What I claim as new and desire to secure by Letters Patent of the United States, is

1. The combination with an encased electrical apparatus having a lead opening in its casing, of a b 1n sa1d opemng formed with an interior chamber and having a perforation extending from said chamber through its wall, a lead provided with a conducting spherical enlargement formed thereon and located interiorly of said chamber, and a conducting formation connected to said casing adapted to pro trulde into the perforation in the bushing wa 2. The combination with an-encased electrical apparatus having a lead 0 ening in its casing, of a bushing in sai ope formed with an interior chamber and having a perforation extending from said chamher through its wall, a lead traversing said bushing and havin a stripped portion interiorly of said cham er, a conducting spherical enlargement formed on the stripped portion of said lead, and a second spherically formed member conductively connected to said casing and arranged to protrude into the perforation in the bushing wall.

3. The combination with an encased electrical apparatus having a lead 0 ning in its casing, of a bushing in sai opening formed with an interior chamber and having a perforation extending from said chamber through its wall, a lead traversing said bushing and having a stripped ortion interiorly of said chamber, a con uotin spherical enlargement formed on sai stripped portion and disposed opposite the perforation in the bushingwall, and a conducting member connected to said casi having a spherical rotuberance and disposed about said bus ng to have said protuberance protruding into the aforesaid perforation.

4. The combination with an encased electrical apparatus having a lead opening in its casing, of a lead passing therethrough, and a bushing therefor. provided interiorly' with a sphere p adapted for discharge from said lead to the casing, and a secondary gap device secured to. the casing wall and provided with a ground discharge connection, whereby abnormal voltages discharge from line to casing and from casing to ground when the casing has attained a predetermined potential.

5. The combination with an encased electrical apparatus having a lead opening in its casing, of a bushing formed with an interior chamber having a perforated wall, a lead in said bushin adapted for abnormal voltage discharge therefrom to said casin through the perforation in the bushing walF and a spark gap device secured to a wall of said casing and having an electrical discharge connection to ground.

6. The combination with an encased electrical apparatus having a lead 0 ning in its casing, of a bushing formed with an interior chamber having a perforated wall, a lead in said bushing provided with a ing support therefor, one of said protuberances being connected to'the casing Wall, the other having a ground discharge connection.

7. The combination With an encased electrical apparatus, of a lead extending from said apparatus through the apparatus casing, means providing a spark gap discharge path from said lead to said casing, and a second means providing a spark gap discharge path from said casing to ground.

In witness whereof, I have hereunto set my hand this 14th day of Feb, 1921.

CHARLES HOWARD KLINE. 

